Frame Part For A Shell-And-Tube Heat Exchanger

ABSTRACT

The invention relates to a frame part for a shell-and-tube heat exchanger. The frame parts should be designed so that given a simplified producibility of the frame parts, a complete compensation for expansion in the longitudinal direction as well as in the transverse direction of the frame part is nevertheless ensured. According to the invention, a frame part for a shell-and-tube heat exchanger comprises a number of tubes, which are parallel to one another, form a tube body, and are flowed through by a heat exchanging medium. The tube body is surrounded by frame parts at least on two sides that are parallel to the tubes. At least one thermal expansion element is formed at least in the frame parts that are oriented parallel to the tubes. The thickness of this thermal expansion element is at least a multiple of that of the material of the frame part where it deviates.

The present invention relates to a frame part for a shell-and-tube heat exchanger.

Shell-and-tube heat exchangers comprise a number of tubes which run parallel to one another and have a heat exchange medium flowing through them. The tubes running parallel to one another form a tubular body. For reasons concerned with stability, handling and installation of shell-and-tube heat exchangers of this type, it is customary for the tubular body to be surrounded by frame parts at least on two sides running parallel to the tubes.

Within the context of heat load cycles occurring during operation of the shell-and-tube heat exchanger, different thermal loading and therefore different thermal expansion of frame parts and tubular bodies take place. In this case, the problem is more serious the greater the length of the tubes. If the frame parts and the outer tubes of the shell-and-tube heat exchanger that are adjacent to frame parts are mounted in a fixed manner with respect to one another, stress peaks occur in particular in the region in which the tubes are attached and put the tightness of the shell-and-tube heat exchanger at risk, in particular in the region in which the tubes are attached. In order to counteract these stress peaks which occur in particular on the outer tubes adjacent to the frame parts, it is customary to provide expansion beads in the frame parts to compensate for the expansion in the longitudinal direction of the frame parts.

Side parts of this type with expansion beads are suitable only for compensating for expansion in the longitudinal direction. None the less, the presence of at least one expansion bead as a weakening of the longitudinal rigidity of the frame part is not sufficient to achieve complete decoupling of tubular body and frame part. In addition, the production of side parts with expansion beads is associated with a high outlay on production and exacting requirements imposed on the forming tools.

By contrast, it is the object of the invention to design the frame parts in such a manner that, with the frame parts being simplified to produce, complete compensation of the expansion in the longitudinal direction and, in addition, also in the transverse direction of the frame part is nevertheless ensured.

The object on which the invention is based is achieved by a shell-and-tube heat exchanger according to the independent claim.

A frame part for a shell-and-tube heat exchanger according to the invention has a number of tubes which run parallel to one another, form a tubular body and through which a heat exchange medium flows. In this case, the tubular body is surrounded by frame parts at least on two sides running parallel to the tubes. At least one thermal expansion element which, in a deflection of the material of the frame part, is at least a multiple of the material thickness thereof, is molded into the frame parts which are aligned parallel to the tubes.

Such a deflection in the shape of the frame part has the effect that not only is a reduced longitudinal rigidly produced but so to is flexibility in the direction transverse to the profile of the frame part. By this means, it is possible not only to intercept the thermal expansion of the tubular body along the direction of the profile of the tubes but also in a transverse direction thereto. At the same time, the introduction of stresses caused by a change in temperature to the tubes on account of different thermal expansion between tubular body and frame parts is avoided. In particular, the roots of the tubes on other components, which roots have been produced, under some circumstances, by welding or soldering, are relieved from stress, and increased quality and reduced leakages of the tubes in these regions are advantageously achieved.

An advantageous refinement of the thermal expansion element makes provision for it to be composed of the material of the frame part itself. This means that the frame part together with the thermal expansion element is composed of components of the same physical behavior and if, according to an advantageous refinement, it is connected integrally to the frame part at least on one side, it can be produced from one piece of material. Particularly preferred refinements of the invention make provision for frame part and thermal expansion element to be connected integrally to each other on both sides of the thermal expansion elements, so that the entire unit can be produced from a single piece of material.

According to a further preferred refinement of the invention, the thermal expansion element is of essentially Ω-shaped design, with the thermal expansion element in particular protruding out of the plane of the frame part away from the tubes. According to a preferred further refinement, in the region of the thermal expansion element a height offset can be formed in the plane of extent of the frame part on both sides of the thermal expansion element. A height offset of this type has the advantage that the frame part can compensate for different heights, for example between a collecting body, into which the tubes lead, and the tubes themselves and at the same time also has great flexibility and low rigidity both in this vertical direction and in the direction of longitudinal extent of the frame part.

Another advantageous refinement of the invention makes provision for two Ω-shaped partial sections to be formed one behind the other, the sections of curvature of which preferably lie on the mutually opposite sides of the frame part. In this case, the thermal expansion element can in particular include a height offset in the plane of extent of the frame part on both sides of the thermal expansion element. Such a double-Ω-shaped design makes it possible to integrate a large length of material into the thermal expansion element and therefore, in particular in the longitudinal direction of the frame part, also to integrate a high degree of thermal expandability.

A further refinement of the invention makes provision for the thermal coefficient of expansion of the frame part in the region of the thermal expansion element to be at most equal to, preferably smaller than, the thermal coefficient of expansion of the tubes. This measure ensures that the expandability of the frame part in the direction of extent of the tubes is at most equal to it, preferably smaller than it, and therefore loading due to different thermal expansion between frame part and tubes is largely avoided. In a refinement of this type, an adaptation to the thermal behavior of the tubes in the case of temperature fluctuations is therefore achieved not only by low mechanical rigidity of the frame part but also by an appropriately high degree of thermal expansion in the region of the expansion element.

According to further refinements of the invention, the thermal expansion element is designed as at least one web which does not extend over the entire width of the frame part. The thermal expansion element preferably comprises two such webs which run on both sides to form a continuous edge with the frame part. This measure firstly achieves a lower mechanical rigidity and therefore better expandability of the frame part in the region of the thermal expansion element in the longitudinal direction of the frame part and secondly material is advantageously saved, which leads to the frame part having a lower weight which constitutes a desired advantageous measure. By two webs forming a continuous edge, a closed rectilinear outer contour of the frame part is maintained at the same time.

According to a further refinement of the invention, a thermal expansion element is formed in at least one section of the frame part that corresponds to an end region of the tubes. This is preferably the region of a fastening, in particular fastening by welding or soldering, of the tubes to another body, such as a collecting tube or a distributor tube. The tubular body of a heat exchanger extends in particular between a distributor tube and a collecting tube, with the inflowing heat exchange medium first of all being guided into the distributor tube and the mass flow being distributed by the distributor tube to the different tubes of the tubular body, thus achieving an enlargement of the surface area of the heat-conducting elements, which promotes the exchange of heat. The partial flows are collected again in the collecting tube and the entire flow is brought together. In a large number of refinements, in particular “monoblock heat exchangers”, the tubes of the tubular body are in each case fastened on both sides by welding or soldering into corresponding holes on the distributor tube and collecting tube. These fastening points, in particular, constitute particular weak points with regard to the mechanical rigidity of the shell-and-tube heat exchanger. Owing to the fact that the thermal expansion element is formed in particular in this end region of the tubes, great flexibility of the frame part is produced here. The frame part extends in particular over the entire length of the tubes between the collecting tube and the distributor tube and has a respective thermal expansion element in the end region of the tubes, in particular on both sides.

A further advantageous refinement of the invention makes provision for external ribs which surround the tubes and are contacted thermally by these tubes to be provided. These external ribs are aligned in particular transversely to the longitudinal direction of the tubes and, in particular on the end, bear at least on one side against a frame part and are preferably connected thereto. The external ribs which are contacted thermally increase the heat exchange surface, with the transfer of heat between the external ribs taking place by thermal conduction in the material. In order to ensure a secure position of the external ribs and good support of the external ribs protruding on the end side, said external ribs are fastened to the frame part. The fastening can advantageously take place by means of hard soldering. The frame parts therefore provide a closed body.

According to a further, particularly material-saving and lightweight refinement of the frame part, the latter is reduced between the thermal expansion elements to a meandering material web which has planiform material tongues which preferably protrude laterally and are aligned in the plane of the frame part. In this case, it is possible in particular for the external ribs surrounding the tubes to be connected in the region of the material tongues to the frame part, in particular by welding or soldering.

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the drawing, in which:

FIG. 1 shows a first embodiment of a frame part according to the invention;

FIG. 2 shows a side view and top view of a second embodiment of a frame part according to the invention, with a height offset being integrated here in the region of the expansion element into the frame part;

FIG. 3 shows a heat exchanger with a frame part according to FIG. 2;

FIG. 4 shows a further embodiment of a frame element according to the invention; and

FIG. 5 shows a heat exchanger with a frame part according to FIG. 4.

FIG. 1 shows the frame part 10 which is divided by the two thermal expansion elements 11, which are integrated into the frame part, into two outer sections 12 and a central piece 13. It can be seen in the enlarged partial detail that the thermal expansion element 13 is formed from a web 14 which describes an essentially Ω-shaped curve and extends as far as the edge, i.e. the outer contour of the frame part 10. In this case, the width of the web 14 is smaller than the width of the frame part 10, with the result that a respective web 14 is arranged on the edge on both sides and a central section 15 which is free from material is situated in between.

FIG. 2 shows a longitudinal section and a top view of another frame part 10 in a sectional illustration. In this case, a thermal expansion element 11 which is formed from two webs 14 is situated between a central piece 13 and an outer section 12, the webs 14 running to the outer section 12 in a manner forming a continuous edge in the contour while the central piece 13 has a greater width than the outer section 12. In this case too, there is a central section 15 which is free from material between the two webs 14. This obtains a saving on material and weight and reduces the mechanical rigidity. Furthermore, the design of the frame part of FIG. 2 corresponds essentially to the design of the frame part of FIG. 1. However, there is a height offset h between the outer section 12 and the central section 13 in the region of the thermal expansion element 11.

FIG. 3 shows the installation position of a frame part 10 according to FIG. 2 on a heat exchanger 30. The heat exchanger 30 is bounded laterally by the distributor tube 31, into which the heat exchanger medium flows, and a collecting tube 32 from which the heat exchanger medium flows out again, with tubes which run parallel and are not illustrated in detail and external ribs running transversely to the tubes being situated between distributor tube 31 and collecting tube 32 and forming the tubular body 33.

The central piece 13 of the frame part 10 extends along the profile of the tubular body and parallel to the profile of the tubes in the tubular body while a respective thermal expansion element 11 is formed in the transition between collecting tube 32 and tubular body 33 or distributor tube 31 and tubular body 33, as is apparent, for example, from FIG. 2, and connects the central piece 13 of the frame part 10 to an outer section 12 which is situated in each case on the outside and is fastened to the collecting tube 32 or distributor tube 31.

If the temperature of the heat exchange medium flowing through the heat exchanger changes, then distributor tube 31 and collecting tube 32 expand especially in the vertical direction while the tubes of the tubular body 33 change especially in the direction of extent of the frame part 10, i.e. in the longitudinal direction. A change in length in two different directions independent of each other is therefore provided, with, in particular, the change in length of the distributor tube 31 differing from that of the tubular body 33. The different expansion in the vertical direction is compensated for via the variability in the height offset h while the exchange in the longitudinal direction in the profile of the tubes takes place via the Ω-shape of the thermal expansion element 11.

The thermal expansion elements 11 of the frame part 10 are situated in particular in the section in which the transition between the distributor tube 31 or the collecting tube 32 and the tubes of the tubular body 33 is provided, which section is a particular structural weak point.

FIGS. 4 and 5 show a further refinement of a frame part according to the invention, with the frame part 10, here too, in turn having two outer sections 12 and a central piece 13 which are connected to one another via a respective thermal expansion element 10 which deviates by a multiple of the material thickness of the material of the frame part 10 out of the plane of the frame part 10, which plane is defined in particular by the plane of the central piece 13. In this case, for reasons concerned with stability and weight and in order to ensure good thermal flexibility of the frame part 10, the central piece 13 of the frame part 10 is reduced to a meandering material web 16 from which material tongues 17 protrude in some sections, said material tongues bearing against the tubular body 33 of the heat exchanger 30 and being fastened thereto. In this case, FIG. 4 shows a sectional illustration corresponding to FIG. 2 while FIG. 5 shows a perspective partial view of a heat exchanger corresponding to FIG. 3. 

1. A shell-and-tube heat exchanger, in which a heat exchange medium flows through a number of tubes which run parallel to one another and form a tubular body, the tubular body being adjoined by a frame part at least on one side running parallel to the tubes, wherein Ω-shaped thermal expansion elements which are deflected out of the plane of the frame part by a multiple of the material thickness of the material of the frame part are molded at least into the frame parts which are aligned parallel to the tubes.
 2. The shell-and-tube heat exchanger as claimed in claim 1, characterized in that the thermal expansion elements are made from the material of the frame part.
 3. The shell-and-tube heat exchanger as claimed in claim 1, wherein the thermal expansion elements are connected integrally to the frame part at least on one side.
 4. The shell-and-tube heat exchanger as claimed in claim 1, wherein the Ω-shaped thermal expansion element comprises a height offset (h) in the plane of extent of the frame part on both sides of the thermal expansion element.
 5. The shell-and-tube heat exchanger as claimed in claim 1, wherein two Ω-shaped partial sections are formed one behind the other, the sections of curvature of which preferably lie on the mutually opposite sides of the frame part, the thermal expansion element in particular including a height offset (h) in the plane of extent of the frame part on both sides of the thermal expansion element.
 6. The shell-and-tube heat exchanger as claimed in claim 1, wherein the thermal coefficient of expansion of the frame part in the region of the thermal expansion element is at most equal to the thermal coefficient of expansion of the tubes.
 7. The shell-and-tube heat exchanger as claimed in claim 1, wherein a thermal expansion element is designed as at least one web which does not extend over the entire width of the frame part and is preferably formed from at least two webs which form a continuous edge in particular on both sides of the frame part.
 8. The shell-and-tube heat exchanger as claimed in claim 1, wherein a thermal expansion element is formed in a section of the frame part that corresponds to an end region of the tubes, preferably in the region in which the tubes are fastened by welding to another body, such as a collecting tube or a distributor tube.
 9. The shell-and-tube heat exchanger as claimed in claim 8, wherein thermal expansion elements are formed in each case on both sides in the section of the frame part that corresponds to the end region of the tubes.
 10. The shell-and-tube heat exchanger as claimed in claim 1, wherein external ribs which are thermally contacted by the tubes are provided, which external ribs are aligned in particular transversely to the longitudinal direction of the tubes and, preferably on the end, bear at least on one side against a frame part, in particular are connected thereto.
 11. The shell-and-tube heat exchanger as claimed in claim 1, wherein the frame part is reduced in sections between Ω-shaped thermal expansion elements to meandering material webs which have planiform material tongues which preferably protrude laterally and are aligned in the plane of the frame part. 